Help explain to me gear ratio

[GoneFishingLTN]

Gear ratio difference 

TTUMQLT2500D-XHRight/Left

6.2:1

6.78/240, 10/2108BB + 

IPT:34.5

 

vs

 

 

Model VF2500HGF

Gear Ratio 6.0:1

Line Retrieve
Per Crank

35in

[bulldog1935]

R = Gear ratio is how many times the spool turns for one turn of the handle (it's the number of teeth on the main gear divided by the pinion gear teeth).   

I = Pi-times-spool-diameter (inches) is how much line one turn of the spool picks up.  

Multiply R X I = IPT = inches of line picked up by one turn of the handle.  

 

 

[WRB]

Same formula works for spinning reels.

The difference being spool is fixed and line is wrapped onto the spool via bail.

Spinning spool are larger in diameter and narrower compared to casting reels. Since there isn’t a standard to control spool size every  mfr is different.

Apples vs oranges understanding IPT.

Because it’s difficult to know the spooled line diameter before or after a cast the only method is measure how many inches of line is recovered with 1 full 360 degree handle turn.

Tom

[bulldog1935]

The "formula" is 4th grade algebra.  

The significant digits matter in a NASA trajectory.  

They don't matter in a crankbait retrieve.  

 

Yes, they were teaching algebra in 4th grade - you just didn't know it.  

 

I can also guarantee they used the algebra and not the calculus to report IPT for reel models (otherwise, they would report it as formula for line diameter)

 

[casts_by_fly]

As the guys covered, its how many times the spool (baitcaster) or bail (spinning) turn per turn of the handle.  Retrive ratio is how many inches of line are pulled in per turn of the handle.  That's a combination of retrieve ratio and spool size and a better way to think about how 'fast' your reel is. I have an 8:1 reel that only pulls in 29" per turn while another is 33" per turn from the same maker.  The difference is spool size.  Whether it matters to you pulling in a lure is another story (I'd argue it does sometimes, but mostly not).

 

Another thing to note, changing the handle to a longer handle does not impact the gear ratio or the IPT measurement.  It just means your hand goes a longer distance per turn of the handle.  That doesn't change the spool/gearing/IPT.

 

2 minutes ago, bulldog1935 said:

The "formula" is 4th grade algebra.  

The significant digits matter in a NASA trajectory.  

They don't matter in a crankbait retrieve.  

 

I don't know about you, but they weren't teaching algebra in my 4th grade.

[The Maestro]

Inches per turn is going to vary depending on how much line is on the spool. I don't know how they come up with their IPT number but I'm assuming it's based on having a full spool. At the end of a long cast, that number could be significantly less.

[Huckfinn38]

Im probably on my own here but I look more at IPT than I do gear ratio.  For me I like a 23-26 ipt reel for crankbaits, a 28-30 ipt reel for Spinnerbaits/Chatterbaits/Lipless Crankbaits, and a 30-32 ipt reel for jigs/texas rig/wacky/dropshot.

[WRB]

I beg to differ. 100 size bait casters with standard spools have increased the gear ratio’s to compensate for the loss of IPT vs legacy larger diameter and wider spool reels.

I changed from 6.3:1 ratio reels to 8:1 to off set the 40% loss of IPT after a long cast using .012D line.

The BFS shallow spools with small diameter .006D line loose less circumference during the same length cast reducing the IPT change significantly.

Something over looked by most anglers.

Tom

[MN Fisher]

IPT is what I look at - and as Tom said, that's gonna change depending on how much line is on the spool at any given moment...I just use it as a reference number.

 

Also noted is spinning vs casting...two reels I own

Casting: Pflueger Patriarch - 7.1:1 ratio - 29IPT

Spinning: Shimano Miravel 2500 - 5.0:1 ratio - 29IPT

[Mobasser]

Faster gear ratio reels help when you get a strike, and need to quickly take in slack line before a hook set.

[Kev-mo]

How much does IPT vary with regard to how much line is on the spool? Is it statistically significant to me as a fisherman? I mean has anyone done any experimentation? To further that how does the manufacture determine IPT? Is it just a formula answer R X I = IPT? Does someone actually measure the IPT at empty, half full and full spool and then take an average. I know, silly questions but still....

[Team9nine]

40 minutes ago, Kev-mo said:

How much does IPT vary with regard to how much line is on the spool? Is it statistically significant to me as a fisherman? I mean has anyone done any experimentation? To further that how does the manufacture determine IPT? Is it just a formula answer R X I = IPT? Does someone actually measure the IPT at empty, half full and full spool and then take an average. I know, silly questions but still....

 

From a post I made 8 years ago on the subject, but yeah, I've played with it  My guess would be IPT as stated by the manufacturer is based on what they consider a full spool, and simply a single actual measurement one time.

 

 

"I read Tom's comment with interest and had some time to kill last night, so I grabbed a reel and started measuring. I had a Shimano Castaic CA200 sitting around that I won't be using any more before things freeze up over here. Capacity is listed at 125 yds of 14# test. I had a nearly full spool of16# fluorocarbon on it. It has a 6.2:1 gear ratio, and the tested IPT was around 24.5"

The initial starting diameter of the line filled spool was 1.233" (radius = 0.616"). After stripping off about 40 yds of line, the effective gear ratio only dropped to just above 5:1. That would be about as long a cast as I'd normally ever make with that outfit. I kept stripping line off, passing the 82 yd mark that is factory placed on the line and continuing until I had nearly 100 yds stripped off. At this point the filled diameter was just 3/4 of an inch, with a spool radius of 0.385". I was well into my backing and likely only had another 20 or so yds of line left as I could see my arbor knot starting to appear. The calculated "effective gear ratio" at that point was 3.9:1 which was an IPT of 15", a 37% decrease from initial starting capacity.

Your mileage will certainly vary, as every reel is different, and a lot of variables affect the overall outcome. In general though, I'd say a typical long cast will likely decrease your overall effective gear ratio by at least 1+ spool revolutions per handle turn (a 7.x:1 becomes a 6:1, etc.). This would only happen during the initial part of your retrieve. As the line gets built back on the spool, the effective gear ratio continues to climb back to "normal." Wider spool reels would probably show less of an effect because they hold more of the line on the "outside" of the spool, while heavier lines, because they are thicker diameter, would likely exaggerate this effect.

I also carried out the "shoe test" at all stages (as suggested in one of my other posts). At full spool and attached to a 6' musky rod, it was a big struggle to lift and wind a 10.4 oz. shoe off the ground using only the reel handle and the drag clamped down. After stripping off the 100 yds of line and retesting, even though the gear ratio is still technically 6.2:1, since your IPT has decreased so much, the effective gear ratio of 3.9:1 made the task a pretty simple affair. A very noticeable difference and considerably easier to accomplish with much less effort in winding."

[WRB]

My hook setting technique using jigs after making a cast between 100’ to 120’ on average is taking line using my reel then a firm rod sweep after the line snug. The reel needs to take up slack and any bow in the line quickly therefore IPT is important.

Today’s 100 &70 size casting reels are smaller, lighter with smaller dia and narrower spools that directly impact IPT. The increased gear ratio is important to move line when needed.

Tom